Carnian

The Carnian (less commonly, Karnian) is the lowermost stage of the Upper Triassic series (or earliest age of the Late Triassic epoch). It lasted from 237 to 227 million years ago (Ma).[2] The Carnian is preceded by the Ladinian and is followed by the Norian. Its boundaries are not characterized by major extinctions or biotic turnovers, but a climatic event (known as the Carnian Pluvial Event) occurred during the Carnian and seems to be associated with important extinctions or biotic radiations.

For the Carnian Alps, see Carnic Alps.

System/ Period	Series/ Epoch	Stage/ Age	Age (Ma)
Jurassic	Lower/ Early	Hettangian	younger
Triassic	Upper/ Late	Rhaetian	201.3	~208.5
		Norian	~208.5	~227
		Carnian	~227	~237
	Middle	Ladinian	~237	~242
		Anisian	~242	247.2
	Lower/ Early	Olenekian	247.2	251.2
		Induan	251.2	251.902
Permian	Lopingian	Changhsingian	older
Subdivision of the Triassic system according to the ICS, as of 2020.[1]

Stratigraphic definitions

Alluvial plain red clays of the Travenanzes Formation, upper Carnian, the Dolomites, northern Italy

Brotheotrachyceras brotheus from the San Cassiano Formation, Val Badia, Dolomites, Southern Alps. This ammonoid is an index fossil for the lower Carnian

The Carnian was named in 1869 by Mojsisovics. It is unclear if it was named after the Carnic Alps or after the Austrian region of Carinthia (Kärnten in German)[3] or after the Carnia historical region in northwestern Italy. The name, however, was first used referring to a part of the Hallstatt Limestone cropping out in Austria.[3]

The base of the Carnian stage is defined as the place in the stratigraphic record where the ammonite species Daxatina canadensis first appears. The global reference profile for the base is located at the Stuores-Wiesen near Badia in the Val Badia in the region of South Tyrol, Italy.[4]

The top of the Carnian (the base of the Norian) is at the bases of the ammonite biozones of Klamathites macrolobatus or Stikinoceras kerri and the conodont biozones of Metapolygnathus communisti or Metapolygnathus primitius.

Subdivisions

There is no established, standard usage for the Carnian subdivisions, thus, while in some regional stratigraphies a two-substage subdivision is common:

• Julian
• Tuvalian

others prefer a three-substage organization of the stage as follows:

• Cordevolian
• Julian
• Tuvalian

Biostratigraphy

In the Tethys domain, the Carnian stage contains six ammonite biozones:

• zone of Anatropites spinosus
• zone of Tropites subbullatus
• zone of Tropites dilleri
• zone of Austrotrachyceras austriacum
• zone of Trachyceras

Paleogeography and climate

The paleogeography of the Carnian was basically the same as for the rest of the Triassic. Most continents were merged into the supercontinent Pangaea, and there was a single global ocean, Panthalassa. The global ocean had a western branch at tropical latitudes called Paleo-Tethys. The sediments of Paleo-Tethys now crop out in southeastern Europe, in the Middle East, in the Himalayas, and up to the island of Timor.

The extreme land-sea distribution led to "mega-monsoons", i.e., an atmospheric monsoon regime more intense than the present one.

As for most of the Mesozoic, there were no ice caps. Climate was mostly arid in the tropics, but an episode of wet tropical climate is documented at least in the Paleo-Tethys. This putative climatic event is called the "Carnian Pluvial Event", its age being between latest early Carnian (Julian) and the beginning of late Carnian (Tuvalian).

Carnian life

In the marine realm, the Carnian saw the first abundant occurrences of calcareous nannoplankton, a morphological group including the coccolithophores.

Invertebrates

There are a few invertebrates which are typical and characteristic of the Carnian. Among molluscs, the ammonoid genus Trachyceras is exclusive to the lower Carnian (i.e., Julian of the two-substages subdivision, see above). The family Tropitidae and the genus Tropites appear at the base of the upper Carnian (Tuvalian). The bivalve genus Halobia, a bottom-dweller of deep sea environments, differentiated from Daonella at the beginning of this age. Scleractinian coral reefs, i.e., reefs with corals of the modern type, became relatively common for the first time in the Carnian.

Vertebrates

The earliest dinosaur Eoraptor originated during the Carnian, around 230 Ma. The oldest well documented dinosaurian assemblage, in the Ischigualasto Formation of Argentina, is most probably late Carnian in age.

In this stage the archosaurs became the dominant faunas in the world, evolving into groups such as the phytosaurs, rhynchosaurs, aetosaurs, and rauisuchians. The first dinosaurs (and the pterosaur Carniadactylus) also appeared in this stage, and though at the time they were small and insignificant, they diversified rapidly and would dominate the fauna for the rest of the Mesozoic. On the other hand, the therapsids, which included the ancestors of mammals, decreased in both size and diversity, and would remain relatively small until the extinction of the dinosaurs.

Conodonts were present in Triassic marine sediments. Paragondolella polygnathiformis appeared at the base of the Carnian stage, and is considered a characteristic species. A partial list of Carnian vertebrates is given below. Many Carnian vertebrates are found in Santa Maria Formation rocks of the Paleorrota geopark.

Chondrichthyans

Chondrichthyes of the Carnian
Taxa	Presence	Location	Description	Images
Mooreodontus	Triassic	England, Germany, India	An xenacanth elasmobranch	Mooreodontus

Actinopterygians

Actinopterygii of the Carnian
Taxa	Presence	Location	Description	Images
Birgeria	Triassic	China, Slovenia, Italy	A non-neopterygian	Birgeria Saurichthys Semionotus
Dictyopyge	Late Triassic	United States	A redfieldiiform non-neopterygian
Hemicalypterus	Late Triassic	United States	A teleosteomorph (modern ray-fin)
Legnonotus	Late Triassic	Switzerland	A neopterygian
Prohalecites	Middle Triassic to Late Triassic	Austria	A teleosteomorph (modern ray-fin)
Ptycholepis	Middle Triassic to Early Jurassic	Italy	A non-neopterygian
Saurichthys	Triassic	China, Italy	A non-neopterygian
Semionotus	Late Triassic	Germany	A neopterygian
Thoracopterus	Middle Triassic to Late Triassic	Austria, Italy	The earliest gliding fish

Coelacanths

Actinistia of the Carnian
Taxa	Presence	Location	Description	Images
Chinlea	Late Triassic	United States	A mawsoniid coelacanth	Chinlea
Diplurus	Late Triassic to Jurassic	United States	A mawsoniid coelacanth
Graphiurichthys	Middle Triassic	Austria	A coelacanth

Temnospondyls

Temnospondyls of the Carnian
Taxa	Presence	Location	Description	Images
Arganasaurus		Argana Basin, High Atlas, Morocco		Cyclotosaurus Koskinonodon Metoposaurus Pelorocephalus
Cyclotosaurus Cyclotosaurus ebrachensis Cyclotosaurus buechneri Cyclotosaurus robustus Cyclotosaurus intermedius		C. ebrachensis: Schilfsandstein Formation, Baden-Württemberg, Germany C. buechneri: Stuttgart Formation, Westphalia, Germany C. robustus: Blasensandstein Formation, Bavaria, Germany C. intermedius: Krasiejów, Poland
Deltasaurus		Australia
Dutuitosaurus		Argana Basin, High Atlas, Morocco
Koskinonodon		All across the US and India
Metoposaurus		Europe and North America
Pelorocephalus		Northwestern Argentina

†Chroniosuchians

Chroniosuchia of the Carnian
Taxa	Presence	Location	Description	Images
Madygenerpeton	Late Triassic	Madygen Formation, Kyrgyzstan	A stem tetrapod	Madygenerpeton

†Procolophonomorphs

Procolophonomorpha of the Carnian
Taxa	Presence	Location	Description	Images
Leptopleuron	Late Triassic	Scotland	A genus of lizard-shaped parareptile	Leptopleuron

†Sauropterygia

†Pachypleurosaurs

Pachypleurosauria of the Carnian
Taxa	Presence	Location	Description	Images
Keichousaurus	Middle Triassic	China	A sauropterygian	Keichousaurus

†Pistosaurs

Pistosauria of the Carnian
Taxa	Presence	Location	Description	Images
Bobosaurus	Middle Triassic	Italy	A sauropterygian	Yunguisaurus
Yunguisaurus	Late Triassic	China	A sauropterygian

†Placodonts

Placodonts of the Carnian
Taxa	Presence	Location	Description	Images
Henodus	Early Carnian			Henodus Parahenodus
Parahenodus	Late Triassic	Spain
Psephochelys	Late Triassic	China
Sinocyamodus	Tuvalian	China

†Thalattosaurs

Thalattosauria of the Carnian
Taxa	Presence	Location	Description	Images
Anshunsaurus	Middle Triassic to Late Triassic	China		Miodentosaurus Nectosaurus (left) and Thalattosaurus (right)
Concavispina	Late Triassic	China
Miodentosaurus	Late Triassic	Falang Formation, Guizhou, China	A relatively large thalattosaurian, more than 4 metres (13 ft) long
Nectosaurus	Late Triassic	United States
Thalattosaurus	Middle Triassic to Late Triassic	United States
Xinpusaurus	Middle Triassic to Late Triassic	China

†Ichthyosaurs

Ichthyosaurs of the Carnian
Taxa	Presence	Location	Description	Images
Californosaurus				Californosaurus Cymbospondylus Shastasaurus Shonisaurus
Cymbospondylus			An elongate ichthyosaur
Shastasaurus			A large ichthyosaur
Shonisaurus			A large ichthyosaur

†Archosauromorphs and Archosauriformes (non-archosaurian)

Non-Archosaurian Archosauromorphs of the Carnian
Taxa	Presence	Location	Description	Images
Doswellia		Doswell Formation, Virginia	Doswellia was a low and heavily built carnivore.	Doswellia Chanaresuchus Hyperodapedon Longisquama Proterochampsa Tanystropheus Trilophosaurus
Chanaresuchus	Middle Triassic to Late Triassic	Chañares Formation, Argentina	A genus of modest sized proterochampsid.
Gualosuchus	Middle Triassic to Late Triassic	Chañares Formation, Argentina	A genus of proterochampsid archosauriform.
Hyperodapedon Hyperodapedon gordoni Hyperodapedon huxleyi Hyperodapedon tikiensis Hyperodapedon huenei Hyperodapedon mariensis Hyperodapedon sanjuanensis		Europe: H. gordoni India: H. huxleyi H. tikiensis South America: H. huenei H. mariensis H. sanjuanensis	One of the most derived genera of rhynchosaurs and the most widespread and diverse with at least six verified species from Europe, Asia and South America and potentially more species from Africa and North America.
Isalorhynchus genovefae		Makay Formation, Madagascar	A derived rhynchosaur and a very close relative of Hyperodapedon, possibly a species in that genus.
Otischalkia	late Carnian	Lower Dockum Group, Texas	A genus of dubious hyperodapedontind rhynchosaurs.
Longisquama	Middle Triassic to Late Triassic	Madygen Formation, Kyrgyzstan	Archosauromorph with elongate integumentary appendages
Ozimek	late Carnian	Krasiejów quarry, Poland	A genus of gliding reptile closely related to Sharovipteryx. A recent phylogenetic analysis incorporating Ozimek found it as a member of the Tanystropheidae, as a close relative of Langobardisaurus and Tanytrachelos. This may suggest that both Ozimek and Sharovipteryx are members of the clade.
Proterochampsa		Santa Maria Formation, Argentina	A genus of proterochampsid.
Pseudochampsa	229 Ma	Ischigualasto Formation, Argentina	A genus of proterochampsid originally thought as a species of Chanaresuchus.
Raibliania		Calcare del Predil Formation, Italy	A tanystropheid.
Rhadinosuchus	late Carnian — earliest Norian	Santa Maria Formation, Argentina	A genus of proterochampsid.
Tanystropheus			A tanystropheid.
Tanytrachelos		Solite Quarry. Cascade, Virginia	A tanystropheid.
Trilophosaurus			A herbivorous lizard-like allokotosaur that reached up to 2.5 m long.
Tropidosuchus	Middle Triassic to Late Triassic	Chañares Formation, Argentina	A genus of proterochampsid archosauriform.
Zanclodon		All across Europe	Zanclodon is the name formally used for fossil material that might actually belongs to at least two genera of dinosaur from the Late Triassic among other genera.

Archosaurs

†Pseudosuchians (non-crocodylomorphan, non-aetosaurian)

†Non-crocodylomorph, non-aetosaurian Crurotarsans of the Carnian
Taxa	Presence	Location	Description	Images
Gracilisuchus				Gracilisuchus Luperosuchus Ornithosuchus Paleorhinus Polonosuchus Postosuchus Rauisuchus Rutiodon Saurosuchus
Luperosuchus
Ornithosuchus
Paleorhinus
Polonosuchus
Postosuchus
Rauisuchus
Rutiodon
Saurosuchus

†Aetosaurs

†Aetosaurs of the Carnian
Taxa	Presence	Location	Description	Images
Adamanasuchus				Desmatosuchus Stagonolepis
Aetobarbakinoides
Aetosauroides
Coahomasuchus
Desmatosuchus
Gorgetosuchus
Longosuchus
Polesinesuchus
Rioarribasuchus
Scutarx
Sierritasuchus
Stagonolepis
Tecovasuchus

Crocodylomorphs

Crocodylomorphs of the Carnian
Taxa	Presence	Location	Description	Images
Carnufex				Hesperosuchus Revueltosaurus
Dromicosuchus	Late Carnian or early Norian
Hesperosuchus
Parrishia
Revueltosaurus
Trialestes

Avemetatarsalians

†Dinosauromorphs of the Carnian
Taxa	Presence	Location	Description	Images
Alwalkeria		Maleri Formation, Andhra Pradesh, India	A basal saurischian dinosaur	Eodromaeus Eoraptor Guaibasaurus Herrerasaurus Lagosuchus Panphagia Pisanosaurus Silesaurus Staurikosaurus
Blikanasaurus	Disputed: considered Norian by some researchers	Lesotho	A sauropodomorph dinosaur.
Caseosaurus		Tecovas Formation, Texas	possibly a synonym of Chindesaurus
Chindesaurus		Colorado City Formation, Texas, USA	A herrerasaurid dinosaur
Diodorus	Carnian - Norian	Timezgadiouine Formation, Argana Basin, Morocco	A silesaurid dinosauriform
Eodromaeus		Ischigualasto-Villa Unión Basin, Argentine Northwest, Argentina	One of the earliest dinosaurs. Possibly the most basal theropod.
Eoraptor		Ischigualasto Formation, Argentina	One of the earliest dinosaurs. Uncertain affinities.
Euskelosaurus	Disputed: considered Norian by some researchers	Lesotho, South Africa, Zimbabwe	A large robust sauropodomorph, potentially up to 10 meters long.
Gnathovorax		Santa Maria Formation, Rio Grande do Sul, Brazil	A herrerasaurid dinosaur.
Guaibasaurus		Paleorrota, Brazil	An early dinosaur of uncertain affinities, possibly a close relative of Saturnalia.
Herrerasaurus		Argentina	A large herrerasaurid dinosaur.
Ignotosaurus		Ischigualasto Formation, Argentina	A silesaurid dinosauriform.
Ixalerpeton		Santa Maria Formation, Rio Grande do Sul, Brazil	A lagerpetid dinosauromorph.
Lagerpeton	Ladinian - Carnian	Chañares Formation, La Rioja Province, Argentina	A lagerpetid dinosauromorph.
Lagosuchus	Ladinian - Carnian	Chañares Formation, La Rioja Province, Argentina	A basal dinosauromorph.
Marasuchus	Ladinian - Carnian	Chañares Formation, La Rioja Province, Argentina	A basal dinosauriform.
Nhandumirim		Santa Maria Formation, Rio Grande do Sul, Brazil	Basal saurischian dinosaur of uncertain affinities.
Panphagia	Early Carnian	Ischigualasto Formation, San Juan, Argentina	A very basal dinosaur, possibly the most basal sauropodomorph.
Pisanosaurus		Ischigualasto Formation, San Juan, Argentina	A small, lightly built herbivore approximately 1 metre (39 in) in length and 30 centimetres (12 in) in height. Considered to be either the oldest known ornithischian, or a silesaurid
Saltopus	Carnian - Norian	Lossiemouth Sandstone Formation, Scotland	A small dinosauriform.
Saturnalia		Paleorrota, Rio Grande do Sul, Brazil	May have been a primitive sauropodomorph, probably grew to about 1.5 metres (4.9 ft) long
Sacisaurus		Agudo, Rio Grande do Sul, Brazil	A silesaurid dinosauriform.
Sanjuansaurus		Ischigualasto Formation, San Juan, Argentina	A herrerasaurid dinosaur.
Scleromochlus		Lossiemouth Sandstone, Scotland	Likely a basal avemetatarsalian. It's taxonomic status is heavily disputed.
Silesaurus		Silesia, Poland	A silesaurid dinosauriform, measuring over 2 meters long.
Staurikosaurus	Middle Carnian	Paleorrota, Rio Grande do Sul, Brazil	One of the first dinosaurs from the Carnian to be discovered. A herrerasaurid.
Teyuwasu			Possible synonym of Staurikosaurus.

Lepidosaurs

Lepidosauria of the Carnian
Taxa	Presence	Location	Description	Images
Brachyrhinodon	Late Triassic	Scotland	a rhynchocephalian	Brachyrhinodon

†Therapsids (non-mammalian)

†Non-mammalian Therapsids of the Carnian
Taxa	Presence	Location	Description	Images
Exaeretodon		Ischigualasto Formation, Argentnia Paleorrota, Brazil		Exaeretodon Placerias
Placerias		Chinle Formation, Arizona

Mammalia

Mammalia of the Carnian
Taxa	Presence	Location	Discussion	Images
Adelobasileus		Tecovas Formation, Palo Duro Canyon, Texas, USA	Some writers consider Adelobasileus to be a mammal,[5] while those who limit Mammalia to the crown group do not include this genus. In any case, Adelobasileus is thought to be either the common ancestor of all modern mammals or else a close relative of that ancestor.	Adelobasileus

Classic localities and Lagerstätten

The lower Carnian fauna of the San Cassiano Formation (Dolomites, northern Italy) has been studied since the 19th century. Fossiliferous localities are many, and are distributed mostly in the surroundings of Cortina d'Ampezzo and in the high Badia Valley, near the village of San Cassiano, after which the formation was named. This fauna is extremely diverse, including ammonoids, gastropods, bivalves, echinoderms, calcareous sponge, corals, brachiopods, and a variety of less common fossils. A collection of this fauna is exposed in the "Museo delle Regole", a museum in Cortina d'Ampezzo.

The Ischigualasto Formation of the Ischigualasto-Villa Unión Basin in northwestern Argentina yielded a very important vertebrate association, including the oldest dinosaurian assemblage.

The Lagerstätte of the Madygen Formation in Kyrgysztan has provided over 20,000 fossil insects, vertebrates and flora.

References

1. "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. 2020.
2. http://www.stratigraphy.org/index.php/ics-chart-timescale
3. Gradstein, F.M.; Ogg, J.G.; Schmitz, M.D.; Ogg, G.M. (editors) (2012). The Geologic Timescale 2012 (volume 1). Elsevier. p. 687. ISBN 978-0-44-459390-0.CS1 maint: multiple names: authors list (link) CS1 maint: extra text: authors list (link)
4. The GSSP was firstly proposed by Broglio Loriga et al. (1999) and established by Mietto et al. (2012)
5. Lucas and Luo (1993).

Bibliography

• Brack, P.; Rieber, H.; Nicora, A. & Mundil, R.; 2005: The Global boundary Stratotype Section and Point (GSSP) of the Ladinian Stage (Middle Triassic) at Bagolino (Southern Alps, Northern Italy) and its implications for the Triassic time scale, Episodes 28(4), pp. 233–244.
• Broglio Loriga, C.; Cirilli, S.; De Zanche, V.; Di Bari, D.; Gianolla, P.; Laghi, G.; Manfrin, S.; Mastandrea, A.; Mietto, P.; Muttoni, G.; Neri, C.; Posenato, R.; Rechichi, M.C.; Rettori R. & Roghi, G.; 1999: The Prati di Stuores/Stuores Wiesen section (Dolomites, Italy): a candidate Global Stratotype section and Point for the base of the Carnian stage, Rivista Italiana di Paleontologia e Stratigrafia 105, pp. 37–78.
• Furin, S.; Preto, N.; Rigo, M.; Roghi, G.; Gianolla, P.; Crowley, J.L. & Bowring, S.A.; 2006: High-precision U-Pb zircon age from the Triassic of Italy: Implications for the Triassic time scale and the Carnian origin of calcareous nannoplankton and dinosaurs, Geology 34, p. 1009–1012.
• Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
• Gradstein, F.M.; Ogg, J.G., Schmitz, M.D. & Ogg, G.M.; 2012: The Geologic Time Scale 2012, Elsevier.
• Lucas, S.G.; Luo, Zhe-Xi; 1993: Adelobasileus from the upper Triassic of west Texas: the oldest mammal, J. Vert. Paleont. 13, pp. 309–334.
• Mietto, P.; Manfrin, S.; Preto, N.; Rigo, M.; Roghi, G.; Furin, S.; Gianolla, P.; Posenato, R.; Muttoni, G.; Nicora, A.; Buratti, N.; Cirilli, S.; Spoetl, C.; Ramezani, J. & Bowring, S.A.; 2012: The Global Boundary Stratotype Section and Point (GSSP) of the Carnian stage (Late Triassic) at Prati di Stuores/Stuores Wiesen section (Southern Alps, NE Italy), Episodes 35, pp. 414–430.

External links

• GeoWhen Database – Carnian
• Upper Triassic timescale, at the website of the subcommission for stratigraphic information of the ICS
• Norges Network of offshore records of geology and stratigraphy: Stratigraphic charts for the Triassic, , and
• Palaeos Mesozoic: Carnian Age